weatherwiz Posted June 29 Share Posted June 29 Currently, a northwest to southeast oriented warm front resides from the northern Great Lakes region into Canada southeast across Pennsylvania and into portions of the mid-Atlantic. This warm front accelerates northeast through the remainder of Saturday, advecting in a moisture rich, high theta-e airmass into New England with dewpoints likely into the lower 70's by early Sunday morning. Through the day today, a shortwave trough dives into the upper-Midwest and amplifies as it progresses across the northern Great Lakes region towards the northeast. The result will be unseasonably strong wind shear overspreading the region characterized by 40-45 knots of bulk shear. In addition, winds in the lowest levels of the atmosphere in the wake of the warm front may remain more southerly with winds more west-southerly aloft. Where llvl winds remain more backed, large helicity values in the 0-1km and 0-3km are likely with as much as 150 m2s2 in the 0-1km layer and 150-200 m2s2 in the 0-3km layer. At the surface, temperatures are expected to climb into the upper 70's to lower 80's with dewpoints into the lower 70's (even as high as 73-75°F should dewpoint pooling result). Depending on the extent of morning cloud cover and degree of heating, temperatures, especially in the valley, could soar as high as 83-85. Despite marginal mlvl lapse rates (~6 C/KM), the combination of surface temperatures into the lower 80's and dewpoints into the lower 70's may yield moderate instability characterized by MLCAPE values in the 1500-2000 J/KG range and SBCAPE values around 2000-2500 J/KG. It should be interesting to note some forecast model guidance is suggesting MLCAPE values could approach 2500+ J/KG with SBCAPE values exceeding 3000 J/KG. These values are difficult to obtain without mlvl lapse rates ~7 C/KM and greater, however, if surface temperatures can near 85 and dewpoints climb into the 74-75°F range, these values could become obtained. The combination of moderate instability and strong wind shear ahead of an approaching cold front and likely pre-frontal trough development will be more than favorable for scattered-to-numerous thunderstorms developing by early afternoon and organizing into one or multiple convective lines. This combination of ingredients is also supportive for the strongest thunderstorms to produce locally damaging wind gusts and perhaps even a tornado. There are some caveats, however, which may reduce a more organized severe weather episode from occurring. In addition to the marginal mlvl lapse rates, the strongest shortwave forcing remains displaced well to the west of the best overlap of shear/instability with forecast model guidance showing the best shortwave forcing still in southeast Canada between the mid-to-late afternoon. All in all, the expectation is scattered-to-numerous thunderstorms develop across interior southeast New York by early afternoon with activity quickly organizing into one or more convective lines. Should the more extreme instability scenarios verify (MLCAPE > 2000-2500 J/KG) potential for a more widespread damaging wind producing event will increase. Given the larger helicity values, there would even be potential for an embedded tornado or two. Any tornado potential would be highest with any discrete cells which form initially or out ahead of the line. Localized flash flooding will be a concern as well given PWAT values approaching and exceeding 2''. 7 Link to comment Share on other sites More sharing options...
FXWX Posted June 29 Share Posted June 29 Good discussion... I'm always intrigued by severe potential that's preceded by active early morning / daybreak warm front activity. The more robust the morning activity gets the greater the potential for late morning/afternoon clearing / heating. 2 Link to comment Share on other sites More sharing options...
Typhoon Tip Posted June 29 Share Posted June 29 1 hour ago, FXWX said: Good discussion... I'm always intrigued by severe potential that's preceded by active early morning / daybreak warm front activity. The more robust the morning activity gets the greater the potential for late morning/afternoon clearing / heating. You and I have talked about this in the past .. .almost a concomitant morning elevated complex of rains with embedded thunder... Suddenly it clears the hillsides are tinted blue in DP heat. boom 2 Link to comment Share on other sites More sharing options...
weatherwiz Posted June 29 Author Share Posted June 29 1 hour ago, FXWX said: Good discussion... I'm always intrigued by severe potential that's preceded by active early morning / daybreak warm front activity. The more robust the morning activity gets the greater the potential for late morning/afternoon clearing / heating. 30 minutes ago, Typhoon Tip said: You and I have talked about this in the past .. .almost a concomitant morning elevated complex of rains with embedded thunder... Suddenly it clears the hillsides are tinted blue in DP heat. boom Indeed, sometimes how the morning performs with the warm front can be a solid precursor to how the afternoon will perform, especially when you're talking about instability being on the greater end of the spectrum. 2 Link to comment Share on other sites More sharing options...
ct_yankee Posted June 29 Share Posted June 29 Hmm, haven't delved deeply into this yet but at first glance it looks to me like the good shear will be almost entirely gone by the time the main round of storms rolls through SNE around 18 to 21z. So timing issues for sure. On the other hand, that shear will be present for the much earlier round of convection late tonight/early morning Sunday, so maybe a surprise supercell is not out of the question then, although instability will be lacking and convection probably elevated. Midlevel lapse rates look to be a bit better earlier as well. But as usual with these setups in SNE things will change right up until the event, so I will monitor trends and see. One big plus for chasing is simply that it's Sunday. Sunday is pretty much the only day when genuine chasing in SNE is even remotely feasible, so there's that. We will see. 1 Link to comment Share on other sites More sharing options...
CoastalWx Posted June 29 Share Posted June 29 18z stuff kind of meh. Seems like morning showers aren’t in a hurry to leave and mess things up a bit. 1 1 1 Link to comment Share on other sites More sharing options...
weatherwiz Posted June 29 Author Share Posted June 29 10 minutes ago, CoastalWx said: 18z stuff kind of meh. Seems like morning showers aren’t in a hurry to leave and mess things up a bit. I do think clouds/morning precip are going to prevent us from achieving the higher end of the instability potential. I would wager we only get up to around 1500 J of MLCAPE (As opposed to 2000-2500). Localized severe still likely but not getting 2000-2500 will prevent severe from being more widespread. Link to comment Share on other sites More sharing options...
Damage In Tolland Posted June 29 Share Posted June 29 Big uns and day tomorrow. Might be somewhat similar to Wednesday nite The main forecast concern will be the potential for strong to severe t-storms in the afternoon and evening as a strong cold approaches from the west. The increasing forcing for ascent will likely result in a greater areal coverage of storms. Mid level lapse rates are marginal, but the heat and high dewpoints should make up for this with CAPES likely reaching 1500-2500 J/kg in the interior. This instability combined with impressive deep layer shear of 40-50 kt is very favorable for organized storms. Given strong linear forcing ahead of the front, storms will likely organize into line segments or even some sort of QLCS as indicated by all the hi-res CAMs. Damaging wind gusts will be the primary threat, but can`t rule out large hail or even a tornado if any discrete supercells can develop. SPC SREF showing moderate probs of STP > 1. Best chance of severe weather will likely be north and west of I-95 due to marine layer near the coast and CSU machine learning probs and HREF updraft helicity are highlighting the interior for severe weather. Also can`t rule out locally heavy rainfall and flooding from t-storms but severe weather appears to be the greater threat. Link to comment Share on other sites More sharing options...
Damage In Tolland Posted June 29 Share Posted June 29 Wild line tomorrow afternoon 1 Link to comment Share on other sites More sharing options...
Torch Tiger Posted June 29 Share Posted June 29 39 minutes ago, Damage In Tolland said: Wild line tomorrow afternoon that model blows 1 Link to comment Share on other sites More sharing options...
Torch Tiger Posted June 29 Share Posted June 29 3k NAM is funny...has a nice bowing line going through N ORH, then poof right before it hits here. Probably 100% spot on 1 Link to comment Share on other sites More sharing options...
Torch Tiger Posted June 29 Share Posted June 29 WRFs look good Link to comment Share on other sites More sharing options...
Damage In Tolland Posted June 30 Share Posted June 30 2 hours ago, Torch Tiger said: that model blows What about this one? Link to comment Share on other sites More sharing options...
Torch Tiger Posted June 30 Share Posted June 30 49 minutes ago, Damage In Tolland said: What about this one? looked good everywhere but here. 'grats Link to comment Share on other sites More sharing options...
WxWatcher007 Posted June 30 Share Posted June 30 HRRR looks robust with multiple line segments in CT tomorrow. Link to comment Share on other sites More sharing options...
weatherwiz Posted June 30 Author Share Posted June 30 Some interesting looking hodographs too, wouldn't be surprised if initially we saw some supercells. If we do see supercells initially, there could even be some splitting supercells. Tomorrow will be another nowcast day, but the HRRR/NAM continues to be very impressive with the instability. If we see 2000+ MLCAPE develop, I think we'll see a corridor of numerous wind damage reports. I am skeptical we see those values though, with lack of capping and what looks to be a pre-frontal developing early on, I think we're going to pop stuff too early and that will prevent max instability from being realized. Link to comment Share on other sites More sharing options...
ineedsnow Posted June 30 Share Posted June 30 7 minutes ago, weatherwiz said: Some interesting looking hodographs too, wouldn't be surprised if initially we saw some supercells. If we do see supercells initially, there could even be some splitting supercells. Tomorrow will be another nowcast day, but the HRRR/NAM continues to be very impressive with the instability. If we see 2000+ MLCAPE develop, I think we'll see a corridor of numerous wind damage reports. I am skeptical we see those values though, with lack of capping and what looks to be a pre-frontal developing early on, I think we're going to pop stuff too early and that will prevent max instability from being realized. Springfield Link to comment Share on other sites More sharing options...
weatherwiz Posted June 30 Author Share Posted June 30 9 minutes ago, ineedsnow said: Springfield Nice llvl turning there. Lapse rate not too terrible but hate that little warm layer just below 500. Also, that 79F dew may be a bit much 1 Link to comment Share on other sites More sharing options...
Damage In Tolland Posted June 30 Share Posted June 30 Big big day . Biggest uns’ Link to comment Share on other sites More sharing options...
CoastalWx Posted June 30 Share Posted June 30 Got to get these high clouds out. 1 1 Link to comment Share on other sites More sharing options...
HoarfrostHubb Posted June 30 Share Posted June 30 Preparing to be underwhelmed. 1 3 1 Link to comment Share on other sites More sharing options...
jbenedet Posted June 30 Share Posted June 30 Every model has clouds sticking around in eastern sections. Caps the t-storm threat to strong to isolated severe. Gotta be west of 395 I think to get good clearing chances. The clouds were my high probability bet when I paid up for sox tickets. Not going if I’m going to cook in full sun and a soup airmass… 2 Link to comment Share on other sites More sharing options...
CoastalWx Posted June 30 Share Posted June 30 Wonder what that stuff near albany does Link to comment Share on other sites More sharing options...
Damage In Tolland Posted June 30 Share Posted June 30 4 minutes ago, CoastalWx said: Wonder what that stuff near albany does Moving north East and drying up it looks like . Probably leaves a boundary for storms to fire later Link to comment Share on other sites More sharing options...
WxWatcher007 Posted June 30 Share Posted June 30 1 Link to comment Share on other sites More sharing options...
WxWatcher007 Posted June 30 Share Posted June 30 Enhanced on the latest SPC update. Link to comment Share on other sites More sharing options...
Modfan2 Posted June 30 Share Posted June 30 20 minutes ago, CoastalWx said: Wonder what that stuff near albany does Thinking the same thing, does debris from that muck up things later? Think showers earlier here might hurt burning off the clouds here 1 Link to comment Share on other sites More sharing options...
CoastalWx Posted June 30 Share Posted June 30 Nadocast looks fun. We’ll see. Feel like keeping the slight would have been fine. Link to comment Share on other sites More sharing options...
Sey-Mour Snow Posted June 30 Share Posted June 30 HRRR gets violent in SWCT by 1-2pm with several rounds after that. Link to comment Share on other sites More sharing options...
NoCORH4L Posted June 30 Share Posted June 30 Why does the morning kaka always screw things up for us? Seems the rest of the country never has this issue. 2 Link to comment Share on other sites More sharing options...
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